The invention is directed to a hybrid circuit arrangement having a resistance layer applied on at least one side of a plate-shaped substrate of glass or ceramic, and having at least one overload protection arranged on the substrate that is electrically connected to the resistance layer.
Such a hybrid circuit arrangement is known, for example, from German Utility Model DE 93 19 473. Such hybrid circuits with film resistors are particularly utilized as a drop resistor or, respectively, feed resister networks in telecommunication systems and are usually manufactured in thick-film or thin-film technology. Since architectures on an integrated circuit basis have replaced the traditional architectures on the basis of transformers in the meantime, such telephone systems are currently more sensitive than ever to over-voltage and over-current risks in telephone lines. These overload risks can have many different causes, for example lightening strikes, surge voltages induced by neighboring high-tension lines or a direct coupling to high-tension lines.
As disclosed in the aforementioned utility model, thermal fuses are utilized as protection against excessively high long-duration loads, these being fastened such that the dissipated power occurring in case of overload leads to a melting of a solder location at which, for example, a spring clip of the fuse is soldered fast, so that the spring clip soldered fast with prestress snaps away and, thus, interrupts the circuit. Such thermal fuses are in fact cost-beneficial; however, a replacement of the entire hybrid circuit is necessary after a response of the fuses. In regions wherein more outages occur due to a relatively poor infrastructure of the energy and communication networks, an outlay that can no longer be justified quickly results.